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3. On Zoanthus Couchii, Johnston. 

 By E. W. H. Holdsworth, F.L.S., F.Z.S., etc. 



(Radiata, PI. X.) 



The existence in our seas of a compound Zoophyte belonging to a 

 group so essentially tropical as the Zoanthidce, was first made known 

 by Mr. R. Q. Couch, who obtained a small species from deep water 

 near the Cornish coast. It was subsequently described and figured 

 in Dr. Johnston's ' British Zoophytes,' and has been since eagerly 

 sought for, but apparently without success ; or if captured, its cha- 

 racters have not been positively recognized. There is reason, how- 

 ever, to believe that the original description was imperfect ; and it is 

 probable that specimens of a compound Polype, found by Mr. Barlee 

 and others along our northern coasts, and some lately obtained by 

 myself in Torbay, may all be- referred to Zoanthus couchii. They 

 are certainly identical with the animal which Dr. Johnston placed 

 with some hesitation among the Sponges, and described under the 

 name of Bysidea papillosa ; and this was believed by Prof. Edward 

 Forbes to be the same as the Cornish Zoanthus. As the specimens 

 recently found differ in some important particulars from those 

 described by Mr. Couch, I have thought it desirable to point out 

 their characters, and to give some details of certain parts of their 

 structure which are peculiar to the family Zoanthidce, leaving their 

 specific distinctness an open question, until we know more of the 

 original Zoanthus couchii. 



The living polypes now exhibited were dredged on the 12th of 

 October last, in 10 or 12 fathoms water, at about a mile from the 

 eastern headland of Torbay, and, although small, agree in other re- 

 spects with the probably maturer examples from other parts of the 

 coast. The special characters of the Zoanthidce, which consist in 

 their increase by budding, and their mode of distribution over the 

 surfaces to which they are attached, are subject in this species to 

 considerable variation. One group of six polypes on the inside of a 

 valve of Cardium rusticum (fig. 4), is arranged in a linear series as in 

 the typical forms of the restricted genus Zoanthus, and is the result of 

 budding in one direction only ; others are scattered over the surface 

 of a flat stone, and have no perceptible connexion with one another, 

 except in a few instances where two or three of them areunited ; the 

 isolated polypes are perhaps the produce of separate ova, and m time 

 may develope their compound character by the usual process of 

 gemmation. Another form of growth is the one under which this 

 Zoophyte has been most commonly known as Bysidea papillosa, and 

 may be well seen in a remarkably fine specimen from Shetland, and 

 now in the collection at the British Museum. In this example the 

 polypes form a compact group (fig. 3), connected in every direction 

 by a general expansion of the basal membrane, which is extended over 

 the whole outer surface of a small univalve shell, and also lines the 

 interior for a considerable distance. Mr. Alder has observed that a 

 Natica is the usual support for this form of development ; but in this 

 instance the shape of the incrusting mass is more like that of a small 

 Buccinum, or a Purpura. In these varying modes of growth, we 



